FR2594894A1 - FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES - Google Patents

Abstract

a) Fuel injection pump for internal combustion engines. b) Fuel injection pump characterized in that the control apparatus 30 comprises a discontinuity detector 48 which detects discontinuities in the quantity signal flowing back QR and which delivers in the form of detection signals phi A , phi B, phi E, phi 1 to phi 4 the appearance of discontinuities in time or in space measured from a reference point BZ and that thanks to these detection signals phi A, phi B, phi 1 to phi 4 the application of the phi MV control signals is corrected. c) The invention applies to fuel injection pumps for internal combustion engines. (CF DRAWING IN BOPI)

Description

"Fuel injection pump for internal combustion engines".

  The invention starts from a fuel injection pump for internal combustion engines with at least ur. pump piston delimiting a working chamber of

  pump to obtain the injection pressure, with a

  electromagnetic control system, which, to fix the beginning of the repression and the end of the repression, blocks

  or unleashes a load shedding channel with respect to the chamber

  pump, with a measuring device which communicates with the load shedding channel and which measures the amount of return fuel which can not be injected during a discharge stroke of the pump piston and which delivers a electrical signal from

  amount flowing back, and with an electrical appliance

  control ring which according to the feedback quantity signal and the operating variables of the internal combustion engine, such as the load, the rotation speed and the temperature

  applies to the control device control signals

  for blocking or releasing the load shedding channel.

  Such a fuel injection pump, described in the main patent (patent application P 35 04 083.1), has this essential advantage, that the quantity 2.- of fuel to be injected, is determined in a closed control circuit, and in that that the amount of fuel

  injected is determined through the detection

  the amount of fuel flowing back, and failing to inject during a delivery stroke of the pump piston, and is corrected by changing the application of the control signal to the

  electromagnetic control device.

  The object of the invention is to improve this

  fuel injection pump described in the main patent

  the invention relates to a fuel injection pump characterized in that the control apparatus comprises a discontinuity detector which

  detects discontinuities in the quantity signal

  flowing in the form of detection signals, the occurrence of discontinuities in time or in space measured from a reference point, and that, thanks to these detection signals, the application of

control signals is corrected.

  The fuel injection pump according to the invention defined above has the advantage that the determination of the injected quantity is refined thanks to additional information resulting from the measurement of the amount of fuel flowing back. The

  discontinuities likely to be detected in the

  quantity of quantity flowing back by differentiation of this signal, provide conclusions on the beginning

  camming, the beginning of the closure of the disc

  positive electromagnetic control, its instant of

  the opening of the electromagnetic device

  order and the moment of its opening, as well as

the end of camming.

  Thus, using the detection of the start of the cam discharge (bottom dead center of the pump piston), the set dead point can be corrected by 3.- relative to a reference mark and thus defaults

  adjustment during assembly can be compensated.

  Thanks to the detection of the instant of closure of the

  If the control is set, the start of the discharge can be set.

  From the beginning of the closing and the moment of closing of the control device, the dynamic behavior of the control device can be determined

  and, consequently, the moment of the beginning of the opening of the

  positive control can be modified so that the dispersion of the injected quantity is reduced by one

race to another.

  Thanks to other characteristics of the

  advantage of the advantageous supplements and improvements of the fuel injection po.pe defined above

are possible.

  An advantageous embodiment of the invention is characterized in that the maximum value

  of the reprocessed quantity is determined as the maximum

  mum of the flow quantity signal back from

  of the measuring device when, during the total discharge stroke of the pump piston, the

  pump work is released to the load shedding channel.

  Thanks to these provisions, the maximum value of quantity repressed geometrically predefined by the construction

  of the fuel injection pump, is exactly de-

  tected and the fluctuations that occur due to the tolerances of the race of the cane and the wear of this

cam are eliminated.

  An embodiment also advantageously

  of the invention is characterized in that there are two temperature detectors for detecting the temperature of the fuel, one of these detectors being arranged in a measurement chamber of the measuring device while the other

  is placed in a suction chamber filled with

  burant, and which is connected to the working chamber of the 4.-

  pump via a feed channel, tan-

  say that there is provided a first correction member for correcting the feedback flow amount signal, on the one hand, with the difference of the temperature values from the first and the second detector of

  temperature, and, on the other hand, with the temperature value

  the first temperature detector, as well as a

  cond correction element to correct the maximum value of the amount repressed with the difference of the values of

  temperatures from the first and second detections

temperature meter.

  With this arrangement of the temperature sensors, a resulting temperature rise

  flow through the electronic device

  magnetic control, can be detected and so the in-

  influence of temperature changes on values

  measurement can be compensated for more precisely.

  Another advantageous embodiment of the invention is characterized in that the measuring device comprises a measuring cylinder and a measuring piston that can be moved in this cylinder against the acton of a return spring, this piston subdividing the measuring cylinder into a cylinder part connected to the load shedding car and constituting the measuring chamber

  and in a cylinder part opposite to the chamber of

  sure and at the same time constituting a spring chamber

  for the return spring, the flow quantity signal

  feedback being derived from the travel path of this piston, while the cylinder portion opposite the measuring chamber is connected to the suction side of the piston

  pump, preferably by means of a

  to the working chamber of the pump.

  Thanks to these arrangements, besides leakage evacuation from the measuring device, a better dynamic of the piston is also achieved when the measurement volume is evacuated out of

  the measuring chamber, because the pressure wave taking

  in the internal chamber of the pump due to the suction stroke of the pump piston, acts on the rear face of the measuring piston.

  Finally, another form of embodiment

  of the invention is characterized in that the

  positive electronic control is bridged by a drift

  the connection between the pump working chamber and the

  load shedding, and that in this derivation is available

  a check valve with its direction of

  to the working chamber of the pump.

  Thanks to this provision, we create the conditions

  the integration of the control device and the measuring device economically into the

  pump part of the fuel injection pump.

  The invention will be described in more detail

  in the description below with reference to the examples

  embodiment shown in the accompanying drawings in which:

  - Figures 1 and 2 represent respectively

  schematically, a device for injecting

  fuel with a fuel tank, fuel pump

  fuel injection and injection nozzles according to a prerier and a second embodiment, - Figure 3 is a block diagram of

  the fuel injection pump in the fuel injection

  fuel injection according to Figure 1 or 2, - Figure 4 is a diagram of the different

  parameters in the fuel injection pump.

  In the case of the fuel injection device shown schematically in FIG.

  socket 11 is arranged in a pump casing 10,

  the one in which a pump piston 12 accomplishes a displacement

  going back and forth and at the same time a 6.- rotation displacement. The pump piston 12 is driven by a cam drive 13 via a shaft 14 which rotates in synchronism with the rotational speed of the internal combustion engine. The front face of the pump piston 12 and the sleeve 11 define a chamber of

  work 15 of the pump, which is in communication by the in-

  intermediate of a feed channel 16 with a suction chamber 17 in the casing 10 of the pump. This

  suction chamber 17 is supplied with fuel

  shot of a fuel tank 19 through

a delivery pump 18.

  From the working chamber 15 of the pump, the fuel, via a central channel and a radial distribution groove 21 connected to this channel in the pump piston 12, is distributed, for a appropriate position in rotation of the pump piston 12, to discharge bores 22 yes open to the

  periphery of the pump piston 12 while being distributed radially

  lemer.t on this periphery. These delivery holes 22 open into connectors 23 in the pump casing 10, connectors to which are connected pipes

  refueling 25 terminating at the injection nozzles 24.

  On the terminal part, facing the working room

  15 of the pump, the pump piston 12, there is provided on this pump piston 12, longitudinal grooves 26 open towards the front face of the piston and therefore towards

  the working chamber 15 of the pump, these longitudinal grooves

  dinals 26 ensuring, during the suction stroke of the

  pump piston 12, a connection between the channel dtalizenta-

  C tion 16 and the working chamber 15 of the pump.

  The working chamber 15 of the pump is connected to a shedding channel 27 which opens into a

  return channel 28 which, for its part, crosses radial-

  socket 11, and this at a location such that the

  outlet of the return channel 28 during the suction stroke.

7.-

  pump piston 12, is connected via the

  longitudinal grooves 26 to the working chamber 15 of the pump, while during the delivery stroke of the pump piston 12, it is closed by it. Between the working chamber 15 of the pump and the unloading channel 27, there is provided an electromagnetic control device having the shape of an electromagnetic valve 29, which is controlled by an electronic control device 30. The electromagnetic valve 29 is then constituted so that it releases the connection of the

  working chamber 15 from the pump to the duct channel-

  27 in its rest position where it is not

  run and close it in its working position where it is powered. Closing the solenoid valve thus determines the beginning

  the discharge of the fuel injection pump, tan-

  say that the opening of this electromagnetic valve

determines the end of the refulse.

  At the bus. load shedding 27 is connected

  measuring device 31 which measures the quantity of fuel

  rant flowing back and which fails during

  a discharge pump 12 from the pump piston

  injection via the injection nozzles 34.

  This measuring device 31 comprises a measuring cylinder 33 formed in a housing 32 and a measurement piston 34 able to move axially in the cylinder

  measurement. The measuring piston 34 solicited by a resistor

  return spring 35 divides the measuring cylinder 33 into a cylinder part constituting a measuring chamber 36 and into a cylinder part constituting a chamber

  37. The measuring chamber 36 is then in contact with the

  communication with the unloading channel 27, while the spring chamber 37 is connected to the suction side of the pump piston 12, and in this case is connected to the suction channel 16. A path detector, in this case / a 8.- measuring coil 38, detects the displacement position

  axial axis of the measuring piston 34 and delivers an electrical signal

  as a backflow amount, which is applied to the control apparatus 30 and represents the time course of the amount of fuel not reaching the injection nozzles during a discharge stroke of the pump piston 12 At the electronic control device are applied, in the form of electrical signals,

  other measured values and characteristic quantities

  operating conditions of the internal combustion engine, such as the speed of rotation n and the load> of the internal combustion engine, the temperature TAbgas of the exhaust gas, the temperature TEl of the fuel in the measuring chamber 36 and the temperature TK2 fuel

  in the suction chamber 17. The latter two are

  their temperature are delivered respectively by a temperature detector 39 or 40 whose temperature probes enter the measuring chamber 36

  or link in the suction chamber 17.

  The fuel injection device

  Figure 2 is only slightly modified by

  to the preceding fuel injection device

  described with reference to FIG. 19 so that the same constituent parts are assigned the same references. In contrast to FIG. 1, the return channel 28 is eliminated in the case of the fuel injection pump of FIG. 2. In its place there is provided a derivation 41 which bridges the electromagnetic valve 29 and which connects the working chamber 15 of the pump to the

  offload channel 27. On this diversion 41 is

  placed a check valve 42 which blocks the flow in the direction from the working chamber 15 of the pump to the unloading channel 27, and which releases the direction

opposite flow.

  The electronic control device 9- generates control signals or switching pulses for the electromagnetic valve 29 as a function of the feedback quantity signal and the characteristic operating variables of the internal combustion engine, such as that the speed of rotation M,

  the load f t the temperature TAbgas of the exhaust gases.

  For this purpose, the electronic control device 30 represents

  The invention is described in detail in the block diagram of FIG. 3 and includes a first computing device 43 in which a characteristic field of curves is stored which sets according to the speed of rotation n "and the load.

  internal combustion engine, the instants of the application

  control signal to a reference point.

  BZ and referred to in this case by the angles of

  mande. V '. The computation unit determines from the operating characteristic variables ni, and which are applied to it and taking into account the reference reference BZ and the temperature TAbgas of the exhaust gases, a switching pulse for the electromagnetic valve 29, impulse whose front and rear flanks are fixed by the control angles re (q 1 '3). The control apparatus 50 comprises in

  in addition, a second computing unit 44 in which is

  Morisé the injected quantity desired QE soll based

  control angles 1 and 43 for the communication time

  of the electromagnetic valve 29, and this also

  in the operation of parameters of the quantities

  operating ticks that constitute the load i and

  the speed of rotation no. This calculating body

  mine from the control angles q 1 and u 3 applied thereto, the corresponding injection quantity for the characteristic operating variables,

  x of the moment, and delivers the injection quantity of

  In addition, the value of the actual injection quantity is effectively equal to the value of the injection quantity actually elsewhere. The value of the injection quantity w appears at the output of the valve. comparator is applied to the calculator 43 which uses this adjustment gap w to correct the switching times 4 1 or q 3 of the electromagnetic valve, this correction being effected so that the adjustment deviation w become as much as possible nil. The QR signal of the amount flowing in

  return, obtained from measuring devices 31, ar-

  bank, through the entrance 46 of the device

  control electronics 30, firstly to a first

  Correction means 47, in which this feedback quantity signal is corrected to compensate for leaks at the measuring piston 34 of the measuring device 31

  and the variation in density, conditioned by the temperature

  fuel, with the speed of rotation

  born ru. of the internal combustion engine, the value of

  sure 1 of the temperature delivered by the detector of

  temperature 39, and the difference TE1 - TK2 between

  their temperature, which are delivered by the two de-

temperature sensors 39, 40.

  The QR return flow signal taken at the output of the correction member 47 is shown in FIG. 4c as a function of the rotation angle or control angle of the displacement cam.

  of the cam drive driving the pump piston 12.

  Er. taking into account the rotational speed of the internal combustion engine, it is also possible to relate the time in the form of independent variables instead of the control angle. On the other two diagrams of Figure 4 are represented, in the same dependence,

  the evolution of the stroke of the pump piston corresponding to

  It causes the displacement of the cam of the cam drive 13 driving the pump piston, and the travel of the needle of the solenoid valve 29 (diagram at line 1 and diagram b). The discharge stroke of the pump piston 12 begins at the control angle 'A'. At the corner

  control q 1 a switching pulse is applied

  the electromagnetic valve 29, this pulse being again suppressed at the control angle q 3.

  For the control angle q 2 'after the application of the

  switching pulse, the electromagnetic valve 29 is completely closed and for the control angle q 4

  the electromagnetic valve, after removal of the

  switching pulse, is completely open again.

  The differences q 2- 1 and 4 - 43 are the movement times of the needle valve of the electromagnetic valve when closing or when opening the electromagnetic valve 29. At the control angle E, the pump piston 12 reached its top dead center and

  the delivery stroke of the pump piston 12 is terminated

born.

  In the quantity signal flowing in

  turn Q, visible in Figure 4c, one can clearly distinguish

  These discontinuity points are sigrificative for these control angles, so that by detecting points of discontinuities in the quantity signal flowing back. QR angles

  corresponding orders can be exactly

  Res. For this purpose, the control apparatus 30 includes a discontinuity detector 38 which includes a number of operating units 49 to 54 for each of the aforesaid control angles A 'E'A a4. In

  these operating units 49 to 54, the points of dis-

  are detected for example by differentiation and the moment of their appearance in the signal is provided

  compared to the BZ reference mark in the form of

  command keys A E and 1 to q4 The command angle

  A is arranged in a comparator 55 with reference numeral 12.- BZ and the difference is applied to the first calculating member 43. The control angles 4 1 and q 2

  subtracted from each other in a first subtraction

  56 and the control angles L 3 and 44 in a second subtractor 57. The difference values are just like the control angle .E applied to the first calculating member 43. This calculating member 43 uses in the correction switching times of the solenoid valve 29 (control angle, and control angle q 3) not only the adjustment difference between the setpoint injection quantity QE soll and the quantity

  of real injection QE ist 'but also the signals of

  Lastly Mentioned, which are applied to him,

  derived from control angles As' qE and a1 to 4 4.

  The actual injection quantity QE ist is determined from the signal maximum of the amount flowing back and the maximum amount discharged determined geometrically, which can be discharged by the pump pisteron during its discharge stroke from the control angle q A (start of the discharge stroke)

  up to the control angle q (f-rin of the refueling run

  o For this purpose, the exit of the first body

  47 is connected to one of the inputs of a sub-

  Tractor 60 via a maximum detector 59, which measures the maximum QR max 'acting for the common angle q and the corrected QR signal of the quantity flowing back, while at the other input of this subtractor is applied, with the maximum value Q max of quantity repressed, the amount repressed QF. maximum geometrically

  possible. The differential signal at the output of the subtraction

  60 is compensated in a second correction element 61 as a function of the temperature value TK2 delivered.

  by the temperature detector 40 and it is applied to

  the actual value of the injection quantity QE is

paratrooper 45.ist

paratrooper 45.

13.-

  As the maximum QH max value of the quantum.

  is not immovably fixed, but can fluctuate due to cam displacement tolerances and cam wear, this maximum value QH max is measured with the aid of the measuring device 31 when the electromagnetic valve 29 is not in circuit during the discharge stroke. The evolution of the corrected signal

  QR of quantity flowing back to the exit of the gold-

  correction axis 47 during the discharge stroke while the electromagnetic valve 29 is not in operation.

  circuit, that is to say while the connection between the

  pump 15 and the channel 27 is continuously

  open, is shown in dashed lines in Figure 4c

  and designated by QH. The maximum of the quantity signal is

  In return, it can be taken at the output of the maximum detector, and then the maximum value QH max of the repressed quarter, which is applied via

  of a vorte 62 and through a third

  correction unit 63 to a memory unit 64

  2C output of the memory organ 64, to which

  constantly appears the current maximum value QH max of the congestion is connected to one of the inputs of the subtractor 60. The door is then always made passant

  where there are operating conditions of the

  internal combustion engine in which there is no infection, so when the electromagnetic valve 29 does not receive switching pulses from the apparatus

  from ccanr.de 3C. This is the case for a corbus machine

  internalization used as a driving force in what is

  shovel push operation (i = 0). To avoid dynamic measurement errors, the door 62 is further open only when the internal combustion engine has reached a reduced level of rotational speed. For this purpose, a logic unit 65 is connected to the control input of the gate 62, a digital signal of charge <and 14.-

  a digital speed of rotation signal nr being applied

  both inputs of this logic circuit. Both

  This logic circuit 75 assuming the form of an AND gate is then always logically 1 when i = 0 and the rotational speed ri is less than a predefined value n1, and are then always logically 0 when these conditions do not exist. are not fulfilled. When the gate 62 is opened with a "logic signal 1", the max QR output value of the maximum detector 59 is applied

  third correction unit 63, where it is cor-

  with the difference TK1 - TE2 of the temperature values

  temperature detectors 39, 40 and written in the memory device 64 as a maximum value

  QH Max of the amount repressed, the old value previously

  memory is overloaded. Like this,

* a current value of the geometric maximum repressed quantity

  metrically possible, taking into account wear and tear, is always

  available days at subtractor 60.

  All in all, thanks to the large number of correction values that are taken into account for the determination of the switching times of the electromagnetic valve 29, a high precision regulation of the quantity of fuel injected via the electromagnetic valves 29 is obtained.

injection nozzles.

  By taking into account the temperature

  In the determination of the switching times q NV ', i.e. q 1 and' 4, the influence of the fuel density changes due to fuel

fluctuating, is taken into account.

15.-

R E V E N D ICAT IONS

  1.- Fuel injection pump for internal combustion engines with at least one piston of

  pump delimiting a pump working chamber to ob-

  hold the injection pressure, with an electromagnetic device control, which, to set the start of the

  repression and the end of repression, block or

  a load shedding channel compared to the chamber of

  of the pump, with a measuring device

  communicating with the load shedding channel and measuring the amount of return fuel that fails to feed during a delivery stroke of the pump piston and delivers an electrical signal of

  amount flowing back, and with an electrical appliance

  tronic control which, depending on the quantity signal,

  tity flowing back and characteristic quantities

  operating conditions of the internal combustion engine,

  such as load, rotational speed and temperature.

  erature, applies to the control device control signals for blocking or releasing the channel

  load shedding, according to document P 35 04 083.1,

  characterized in that the horn apparatus (30) has a discontinuity detector (48), which detects discontinuities in the feedback quantity (QR) signal, and delivers in the form of detection (<A 'E' '-1 a (4) the occurrence of time or space discontinuities measured from a reference point (BZ), and that with these detection signals (q At E q1 to 4) the application of control signals (A) is corrected 2. Injection pump according to claim 1, characterized in that the control apparatus (30) comprises a field of characteristic curves memorized and which sets according to operating characteristics 16._ of the internal combustion engine, such as the speed of rotation (ri) and the load (D), the

  temperature of the fuel (TKt, TK2), the moments,

  reference point (BZ), the application of the control signals (control angle q V), and that the detection signals (<A '1 4) are used to correct the control angle (q MV) determined from the characteristic curve field for values

  predefined operating characteristics.

  3. Injection pump according to the claim

  2, characterized in that the control apparatus (30) comprises a difference-forming device (60) to which is applied, on the one hand, the maximum value (QRmax) of the quantity signal flowing around (Q). ) and on the other hand, a maximum value of quantity repressed (QHmax)

  for the maximum quantity discharged geometrically possible

  ble (QH), and a comparator (45), to which is applied

  the actual value of the quantity injected (Q.ist)

  d'Utre collected at the exit of the training device

  differences (60) together with the value of

  gne, predefined by the control angle ((), of the injection quantity (QE soll), and that the adjustment deviation which can be taken at the output of the comparator (45) is used to correct the control angle (q MV) *

  4.- Injection pump according to the claim

  3, characterized in that the maximum value (QHma)

  of the reprocessed quantity is determined as the maximum

  mum of the flow quantity signal back from

  of the measuring device (31) when, during the total discharge stroke of the pump piston (12), the working chamber (15) of the pump is released towards the

load shedding channel (27).

  5. Injection pump according to any one

  Claims 1 to 4, characterized in that it is

  two temperature detectors (39, 40) for detecting

  17 - the temperature (TK1, TK2) of the fuel, one of these detectors being disposed in a measurement chamber (36) of the measuring device (31) while the other is arranged in a suction chamber ( 17) filled with fuel and which is connected to the working chamber (15) of the pump via a feed channel

  (16), while a first body of

  tion (47) to correct the feedback flow quantity (QR) signal, on the one hand, with the difference of the temperature values (TK1, TK2) from the first and second temperature sensors (39, 40). ) and other

  on the other hand, with the temperature value (TEl) of the first

  temperature controller (39), as well as a second correction element (63) for correcting the maximum value (Qmax) of the reprocessed quantity with the difference of the values of

  temperature (TEi, TK2) from the first and second

  conz temperature detector (39, 40).

  6.- Injection pump according to any one

  reverbications 1 to 5, characterized in that the provision

  measuring device (31) comprises a measuring cylinder (33) and a measuring piston (34) which can be displaced in this cylinder against the action of a return spring (35), this piston subdividing the cylinder of measuring (33) in a cylinder part connected to the unloading channel (27) and constituting the measuring chamber (36), and in a cylinder part opposite to the measuring chamber (36) and constituting at the same time a chamber of spring (37) for the return spring (35), the quantity signal

  feedback flow (QR) being derived from the flow path

  placing the piston, while the cylinder portion (37) opposite the measuring chamber (36) is connected to the suction side of the pump piston (12), preferably by a supply line (16) terminating at the

  working chamber (15) of the pump.

  7. Injection pump according to claim 6, characterized in that the unloading channel (27) is connected to a return channel (28) which, during the suction stroke of the pump piston (12). ), is connected to the working chamber (15) of the pump, while during the discharge stroke of the pump piston (12), it is

closed by this piston.

  8. Injection pump according to claim 6, characterized in that the electronic control device (29) is bridged by a bypass (41) which connects

  the working chamber (15) of the pump to the drainage channel

  (27), and that in this derivation (41) is arranged

  a check valve (42) with its direction of passage

  lant to the working chamber (15) of the pump.